Dry-aged meat is crazy expensive. But oh man is it delicious. The dean of food science writers, Harold McGee, writes inLucky Peach Issue 2about what makes it taste so good—and what makes other things taste, well, not so good.

Proteins, carbohydrates, and fats are the building blocks of living things, but they don't have much flavor in their natural state. They are bland to begin with. That's why we cook them, why we season them, why we transform them — to make them more appealing to us.

But sometimes we can get our food to make itself more delicious, by treating it in a way that creates favorable conditions for the enzymes that are already in the food to work together in a certain fashion.

Enzymes are molecules that exist in foods-and in microbes intimately involved with food-that can transform those basic, bland building blocks. They're nanocooks-the true molecular cooks. Dry-aging, ripening, and fermentation are all processes that take advantage of enzymes to make foods delicious before cooking.

Most meat, by contrast, is prepared for the market very quickly. The animal is slaughtered, the various parts of the muscle system are separated and packages, and then they're distributed. That's about it.

Dry-aging beef means that once the animal is slaughtered and butchered, portions of the carcass are allowed to rest in very carefully controlled conditions (cool temperatures, with relatively high humidity) for a period of time—often several weeks, and sometimes up to a couple of months.

When we create such conditions, we allow enzymes to do their work. And we end up with a complexity of flavor—savoriness, sweetness, some bitterness-that just wasn't there before. There's no cooking method that can generate the depth of flavor of a dry-aged piece of meat.

What happens is that enzymes in the meat's muscle cells begin to break down the meat's proteins, fats, and glycogen—a carbohydrate—into amino acids, fatty acids, and sugars. One amino acid generated by dry-aging—the most important and flavorful one, in fact—is glutamate, which is part of MSG. other amino acids have flavors somewhat similar to MSG; others still are sweet.

Dry-aging beef also causes it to lose some of its moisture. Meat begins at about 75 percent water; after dry-aging, it may go down to somewhere around 70 percent. It doesn't sound like much of a change, but what it means is that the flavors become more concentrated, and the tissue itself becomes more concentrated, too. Dry-aged meat is still juicy when you cook it, but the juices are even more delicious than usual.

In short, it's wonderful, delicious stuff. It's also really hard to get your hands on, and when you can find it, it's often very expensive—you really have to pay through the nose for it, because it's very expensive to produce. The meat has to be kept in a controlled environment for a long time, and that eats up money. And then you lose a fair amount of the meat's weight, too: you're evaporating moisture, and the surface of the meat begins to spoil, as well. It dries out, it develops unpleasant flavors, and sometimes it develops a bit of mold. It's not harmful, but it needs to be trimmed off before the meat can be sold.

So if dry-aged meat is so hard to find, you might wonder if you can just buy a regular steak and dry-age it in your refrigerator. You can...but it's probably not going to come out very well.

Depending on what else you've got in the fridge, you're going to end up with a piece of meat that may have picked up some other smells and flavors. Opening and closing the refrigerator door is going to mean that the temperature isn't controlled, so you're much more likely to develop mold growth on the surface. And finally, you'll end up having to trim a fair amount of the steak away before you can eat it. Dry-aging is very difficult to do well at home.

But if you want to try it, then what I would recommend is getting a primal cut, a large piece of meat from which you can cut steaks later on . Then the trimming won't be so difficult . Put the meat in a second refrigera- tor that doesn't get used often (if you're lucky enough to have one) . suspend it in a twine harness, or on a rack, so that the entire surface is exposed to the air .

Finally, if you're going to do it, how long should you keep it in there? If you bought the meat from a normal retail store, then it's already about a week old. Hang on to it and experiment—cut a steak off every once in a while and see if you like it. You can take it too far. Once it gets past about six to eight weeks—in my experience, anyway-the flavor becomes so transformed by the action of the enzymes that it begins to taste like blue cheese. It's a very interesting transformation, but for most people, steak that tastes like cheese is not a desirable thing.

On Our Perception of Food

When we experience food, we're doing it through taste receptors on our tongues and smell receptors in our noses. Both of them are important for registering the full flavor of any food. If you deprive yourself of either, food just doesn't taste right.

All of us are born with largely the same apparatus for experiencing taste and smell, but within that general apparatus, there are differences. No one has exactly the same set of genes. We have a few dozen genes that specify what things we can taste, and a few hundred genes that specify what we can smell.

What that means is that to one degree or another, we're all experiencing the world of flavor in slightly different ways—and, for some people, in substantially different ways. That's part of the reason that people have different flavor preferences. Some people are very sensitive to bitter things, and some people can't even detect those very same bitter compounds.

But the major source of difference in people's tastes for different foods is still experience—a combination of personal experience and the experience afforded by culture.

Soap in my Taco

If you grow up in a culture in which a particular flavor is very common, then when you encounter it later on, in adulthood, it may be especially pleasing because it reminds you of childhood. But if you've never experienced a particular flavor or aroma, and then you come across it later on, it might strike you as very strange, even repulsive. The classic example is cilantro. It's an herb that is very common in some cuisines in Asia and Latin America, and not so common in european cultures or, until recently, in the United States. The same compounds that give cilantro much of its flavor are also found in lotions and soaps.

So say you grew up in Vietnam, and cilantro is an everyday part of your experience of food from very early on—then it'll likely be perfectly natural for you when you find it in Mexican food. If you grew up in the United States, on the other hand, and you first encountered those aroma compounds in soaps, then when you go out and have your first Mexican meal (or your first Vietnamese meal) and encounter that same aroma, you might feel like it has no right to be in your mouth. It doesn't belong there, it's disgusting—you spit it out. Your context for that flavor is soap and not food.

That's a cultural, experiential response. You can overcome it, but it takes effort. You have to decide that you want to overcome it, and you have to expose yourself repeatedly to this thing that your body keeps telling you doesn't belong in your mouth.

Why Stinky Cheese Doesn't Stink

But let's get back to the apparatus with which we perceive flavor. There are some really interesting complications that, once you know about them, will help you understand better why some funny things happen in our everyday perception. Take a piece of Époisses with a washed rind, for example. It's really powerful. You can walk into a room and smell it from a distance.

You might think that once you put that in your mouth, it's going to be really, really powerful—it's going to blow your nose out of the water. But in fact, what happens is that when you put a piece of that cheese in your mouth, it's wonderfully aromatic and balanced . Not too strong at all.

The reason is that this apparatus of ours, our smell receptors, operate in different modes at any given moment. When we're breathing in and sniffing, we're sensing by breathing directly from the air around us into our nose . This is called orthonasal perception. When we've put something in our mouth, though, and we're chewing it, then we're breathing out and passing the air across our smell receptors. So the air is going out through our nose, rather than in. That's called retronasal perception.

Our brain can tell the difference between when we're sniffing the air around us and when we're sniffing the air inside our mouths. And it uses a different set of neurons to process that information. The result is heightened attention when we smell Époisses nearby, and pleasure when it's in our mouths.

SuperTasters

Now there's one general misunderstanding that I think is worth addressing, and that's the idea of the supertaster. It's a real designation, but people have misunderstood it to mean people who are really, really good tasters. You hear "supertaster" and you assume that all great chefs are supertasters, and that all super- tasters should be chefs. In fact, that's not what the phrase means at all .

Supertaster is a term that was originally used to identify people who are especially sensitive to a particular bitter chemical compound. It doesn't say anything about one's ability to detect flavors or recognize flavors or anything like that. Now, it's true that some people are born with many more taste buds than other people are, which means that they're more sensitive to flavors than other people. But that's not necessarily a great thing.

If you have lots and lots of receptors, that means that you're extremely sensitive to taste and smell—which means that many of the experiences that you have while eating and drinking can be a little bit too much. You can learn to enjoy these experiences over time, but simply having more taste buds doesn't mean that you're necessarily going to be a better taster, or a better cook, than anyone else. Sorry.